Compressed gas breathing apparatus

ABSTRACT

A pressure reducer is connected between a source of high pressure breathing gas and the inlet of a normally closed pneumatically operated control valve, the outlet of which is connected with a pressure reducing demand valve leading to a facepiece. A tube also connects the breathing gas source with another part of the control valve for holding the latter open as long as the breathing gas pressure remains above a predetermined value, whereby the control valve connects the pressure reducer with the demand valve. A normally closed pneumatically operated alarm valve also connects the pressure reducer with the demand valve, but is formed and constructed to be snapped open by the pressure drop across it only when the demand valve is opened while the control valve is closed due to reduction in the gas pressure below said predetermined value. The pulse of gas created every time the alarm valve opens signals the user that the control valve has closed.

' 14 1 Dec. 4, 1973 COMPRESSED GAS BREATHING APPARATUS [75] Inventor:Layton A. Wise, Washington, Pa.

[73] Assignee: Mine Safety Appliances Company,

- Pittsburgh, Pa.

22 Filed: Oct. 25, 1972 211 App]. No.: 301,461

57 ABSTRACT A pressure reducer is connected between a source of highpressure breathing gas and the inlet of a normally closed pneumaticallyoperated control valve, the outlet of which is connected with a pressurereducing demand valve leading to a facepiece. A tube also connects thebreathing gas source with another part of the control valve for holdingthe latter open as long as the breathing gas pressure remains above apredetermined [52] US. Cl. 222/3, 222/39 value, whereby the controlvalve connects the Prey [51] lllt. Cl B6711 5/32 Sure reducer i thedemand valve. A nofinally [58] Field of Search 222/39, 57, 3; closedpneumatically operated alarm valve also l 128/203; 137/557 nects thepressure reducer with the demand valve, but is formed and constructed tobe snapped open by the [56] References C'ted pressure drop across itonly when the demand valve is UNITED STATES PATENTS opened while thecontrol valve is closed due to reduc- 3,524,424 8/1970 Roland et al. 137557 x tion in the gas Pressure below Said predetermined 3,594,745 7/1971Nickels 137/557 value. The pulse of gas created every time the alarm3,584,596 6/1971 Westcott et al 222/3 valve opens signals the user thatthe control valve has closed.

Primary Examiner-Stanley H. Tollberg Attorney-Brown, Murray et al. 10Claims 5 Draw'ng Figures ALARM-CONTROL VALVE 7 6 /0 CUM/ RESSED P DEMAND0 2 6/15 30 VALVE L, J FACEP/ECE ALARM VALVE PATENTEBBEC 4M5 SHEET 16? 3WQINRGGVK PATENTEUUEB 4197s sum 3 or 3 COMPRESSED GAS BREATHINGAPPARATUS In compressed gas breathing apparatus it is desirable toprovide an alarm to warn the user when the gas pressure falls to a givenlow pressure so that he will know that he is running out of breathinggas. In one system a hell or whistle is sounded as the alarm, but suchan alarm consumes too much of the valuable available gas. Also, undercertain conditions, the signal may not be heard. In another system, highresistance to breathing is used as an alarm, but the intensity of thealarm is directly proportional to the rate of breathing, so duringshallow breathing the alarm is weak and may be unnoticed. Such a systemalso has only one minor abrupt change in the breathing resistance. Ifthe user is breathing shallowly when this change takes place, it may gounnoticed. Furthermore, such a system does not automatically reset.Failure to reset the alarm manually results in no alarm later. Finally,the increased resistance to breathing reduces the flow from theregulator.

It is among the objects of this invention to provide breathing apparatushaving a low pressure alarm which is automatic, which does not impedethe necessary flow requirements of the apparatus, which is not affectedsignificantly by the depth of inhalation, which cannot be overlooked,and which automatically resets itself when the gas pressure is restored.

The preferred embodiment of the invention is illustrated in theaccompanying drawings, in which FIG. 1 is a diagrammatic view of thesystem;

FIG. 2 is an enlarged longitudinal section of the alarm-control valve inits open position;

FIG. 3 is a central longitudinal section of the closed alarm valve;

FIG. 4 is a side view, partly in longitudinal section, showing the alarmvalve open; and

FIG. 5 is a fragmentary cross section taken on the line V-V of FIG. 4.

Referring to FIG. 1 of the drawings, the regulator of the compressed gasbreathing apparatus is shown within the dotted line rectangle. Thisregulator is connected with a suitable source of compressed gas, such asa tank 1 of compressed air, and with a facepiece 2 or mask for the userof the apparatus. The regulator shown includes a pressure reducing valve3, the inlet of which is connected with the compressed gas tank by aconduit 4. Assuming that the tank contains gas under a pressure of 2,000psi, for example, the pressure reducer preferably reduces this pressureto between 65 and 80 psi. The outlet of the pressure reducer isconnected by a conduit 6 to the inlet of a normally closed pneumaticallyoperated alarm-control valve 7, the outlet of which is connected by aconduit 8 with the inlet of a'pressure reducing demand valve 9 of anysuitable well-known construction. The outlet of the demand valve isconnected by a hose 10 with the facepiece 2.

It is a feature of this invention that during normal operation of thebreathing apparatus the high gas pressure at tank 1 maintains thealarm-control valve open so that gas can flow through it from the tankto the facepiece every time the wearer of the facepiece inhales, andthereby opens the demand valve. One way of keeping valve 7 open is toconnect the first conduit 4 to the upper end of the control valve bymeans of a tube 12 to supply high pressure gas to that valve. As shownin FIG. 2, pressure acts on a piston 13 slidably disposed in an axialpassage 14 of the valve housing and moves the piston downwardly. Theenlarged base of the piston supports the upper end of a stem 15 thatextends down through a sleeve 16 rigidly mounted in the housing. Thelower end of the sleeve is provided with an inlet port 17 encircled atits lower end by a valve seat 18. The stem extends downthrough thisport, with its lower end slidably mounted in a bearing 19 encircled byvertical openings 20. Between this bearing and the valve seat, a closuremember 22 is rigidly mounted on the stem. In its lower position that isshown, the piston compressses a coil spring 23 encircling the stembetween the bottom of the sleeve and a collar 24 threaded on the stem.By screwing the collar up or down the stem, the spring pressure can beadjusted so that the closure member 22 will be raised against the valveseat whenever the gas pressure above the piston falls to a predeterminedvalue, such as 600 psi for example. The side of the sleeve is providedwith outlet ports 25 that communicate with the outlet 26 of the valvehousing.

Another feature of this invention is that when the pressure of the gasin the tank falls to a predetermined point or value as mentioned above,so that the user of the apparatus should be warned that his gas supplyis giving out and he should either replace it or remove himself from thearea in which he needs the breathing apparatus, he is warned of thissituation automatically by the apparatus. Accordingly, an alarm valve 30is connected into the system by a conduit 31 extending from this valvesinlet to the outlet of pressure reducer 3 or to conduit 6 leading fromthat outlet. The outlet of the alarm valve is connected by a conduit 32either with conduit 8 connecting the control valve with the demandvalve, or directly to the demand valve itself. This alarm valve normallyis closed as shown in FIG. 3 and is pneumatically operated to open it.It remains closed as long as the control valve is open but when thatvalve closes, due to a reduction in the gas pressure that was holding itopen, the pressure drop across the alarm valve is increased to the pointwhere the alarm valve opens every time the wearer of the facepieceinhales. Also, the alarm valve is so constructed that it opens suddenlywith a snap action at the beginning of each inhalation, so that the usercannot help but notice at feel the momentary increase in flow of gasinto his lungs every time he inhales. These repeated surges or pulses ofgas provide a positive warning to him that he is inhaling through thealarm valve. To accomplish its purpose, the alarm valve may beconstructed as follows.

As shown in FIGS. 4 and 5, the housing of the alarm valve has an inlet35 at its front end and an outlet 36 at its back or downstream end.Inside the housing the marginal area of a closure-supporting diaphragm37 is clamped. The central portion of this diaphragm is provided' withan opening and is clamped between a clamping ring 38 and an annularmetal disc 39 provided with an axial passage 40 aligned with thediaphragm opening. Screws 41 extend through the ring and diaphragm andinto the disc. Behind the disc there is a sleeve 42 encircled at itsfront end by a radial flange 43. The marginal area of a flexiblediaphragm 45 is clamped between this flange and the disc by emans ofcircumferentially spaced screws 46. Between these screws the edge of thedisc is notched and its front is provided with radial slots 47 thatextend inwardly from the notches 48 to holes 49 extending through thedisc around its central passage. Diaphragm 45 is a movable valve closurethat is engageable with a valve seat 50 encircling the inner end ofpassage 40.

The back portion of sleeve 42 extends radially inward around an axiallyadjustable check valve body 51 provided with a central bore 52. There isa small clearance between this body and the sleeve, along which thesleeve can move back and forth. The front end of the inner part of thesleeve forms a check valve seat 53 that normally engages the back of aflexible valve disc 54 provided with a central stem 55 plugged into bore52. Compressed between the front flange 43 of sleeve 42 and the rearwall of the chamber in which the sleeve is located there is a coilspring 56 that urges the sleeve and metal disc 39 toward their forwardpositions shown in FIG. 3, in which the alarm valve is closed. At thistime the gas pressure at the inlet 35 and outlet 36 of this valve issubstantially the same because control valve 7 is open. The flexiblediaphragm 45 is held against its seat because the gas pressure betweenthe diaphragm and the check valve behind it is substantially the same asthe pressure at the alarm valve outlet 36.

Every time the wearer of the mask inhales, the demand valve 9 is openedand the pressure at its outlet is reduced to only a few inches of wateras determined by the setting of that valve. Assuming the control valve 7has just closed, each inhalation reduces the pressure in conduits 8 and32 for a moment to a predetermined value, such as 30 psi, which causes apressure drop through the alarm valve so that support diaphragm 37 andmetal disc 39 immediately move rearwardly against the resistance of thecoil spring. This moves check valve seat 53 back away from valve disc 54and therefore allows the gas pressure directly behind flexible diaphragm45 to drop, whereupon gas pressure in front of the diaphragm unseats itas shown in FIG. 4 to oepn the valve. This opening of the alarm valvewhen inhalation occurs is very quick. It can be termed a snap action.Opening of the valve allows gas from inlet 35 to flow through discpassage 40 and into the space between the metal disc and the flexiblediaphragm and then forward through holes 49 in the disc and radiallyoutward through slots 47 and then back around the disc into the chamberbehind it, from which the gas enters the outlet 36 of the valve.

The sudden surge of gas pressure above what it was a moment before thevalve opened, and the resulting momentary increase in gas flow are feltin the lungs of the inhaler, which inform him of the fact that he isbreathing through the alarm valve 1 and not through its control valve.This warns him that the primary supply of gas is becoming too low inpressure. As gas continues to flow from the alarm valve to the demandvalve during the same inhalation phase, the demand valve recovers tocontrol the pressure, resulting in the pressure at the outlet of thealarm building back up toward the pressure at the inlet so the coilspring can expand and move the metal disc forward to its front position,but the flexible diaphragm 45 remains ofi its seat because the gaspressure directly behind it still is not great enough to seat it. Whenthe user stops inhaling and starts to exhale, the pressure at the alarmvalve outlet becomes substantially the same as its inlet pressure so thepressure between the check valve and the diaphragm becomes great enoughto force the diaphragm forward against its seat to close the alarmvalve. This cycle is repeated every time the user inhales, so he soon,if not immediately, becomes aware of the fact that he is inhalingthrough the alarm valve.

It will be seen that breathing gas is not wasted in operating the alarm,and that the alarm valve resets itself at the end of each inhalation.The alarm device does not impede the necessary flow requirements of theapparatus, and the strength of the alarm pulse is not affectedsignificantly by the depth of inhalation. The control valve reopensautomatically when the tank pressure is renewed to raise it above thealarm pressure.

If a pressure reducing demand valve is used that can handle the hightank pressure, the first pressure reducer 3 can be eliminated, but thiswould require a modified alarm-control valve through which the high tankpressure gas could flow. Or, pressure reducer 3 could be placed betweenthe demand valve and conduits 8 and 32.

According to the provisions of the patent statutes, I have explained theprinciple of my invention and have illustrated and described what I nowconsider to represent its best embodiment. However, I desire to have itunderstood that, within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically illustrated anddescribed.

I claim:

1. Compressed gas breathing apparatus comprising a conduit with an inletfor connection to a source of breathing gas under high pressure, anormally closed pneumatically operated control valve with an outlet, anormally closed pneumatically operated alarm valve with an outlet, apressure-reducing demand valve having an inlet connected with said valveoutlets and having an outlet for connection to a facepiece,gasconducting means connecting the outlet of conduit with the inlets ofsaid control and alarm valves, said control valve containing pneumaticpressure actuated means for holding it open as long as said gas pressureremains above a predetermined value to thereby connect said conduit withthe demand valve, the alarm valve being formed and constructed to beopened abruptly by the pressure drop across it every time the demandvalve is opened while said control valve is close due to reduction insaid gas pressure below said pre-determined value, whereby to create apulse of gas at the outlet of the demand valve that will signal the userof the apparatus that the control valve has closed.

2. Compressed gas breathing apparatus according to claim 1, in whichsaid gas-conducting means is a pressure reducer.

3. Compressed gas breathing apparatus according to claim 2, including atube connecting said conduit with said pressure actuated means in thecontrol valve for applying said gas pressure thereto to hold the controlvalve open.

4. Compressed gas breathing apparatus according to claim 3, in whichsaid control valve includes a valve port encircled by a seat between theinlet and outlet of that valve, a closure member, and a spring normallyholding said closure member against said seat, and said pressureactuated means includes a piston operatively connected with said closuremember for moving it away from said seat against the resistance of saidspring, the control valve having a passage connecting said tube withsaid piston.

5. Compressed gas breathing apparatus according to claim 4, includingmeans for adjusting the pressure exerted by said spring, whereby tocontrol said predetermined value of said gas pressure.

6. Compressed gas breathing apparatus according to claim 4, including astem extending through said valve port and rigidly connected to saidpiston and closure member.

7. Compressed gas breathing apparatus according to claim 4, including astem extending through said valve port and rigidly connected to saidpiston and closure member, and a collar threaded on said stem, saidspring being a coil spring encircling said stem and compressed betweensaid collar and valve port.

8. Compressed gas breathing apparatus according to claim 1, in whichsaid alarm valve includes a valve seat, a diaphragm between the seat andthe valve outlet, a normally closed chamber having said diaphragm as onewall whereby a predetermined gas pressure in the chamber will hold thediaphragm against said seat to maintain the valve closed, a normallyclosed check valve for said chamber, and means actuated by said pressuredrop for opening said check valve so that the gas pressure at the valveinlet will force the diaphragm away from its seat.

9. Compressed gas breathing apparatus according to claim 8, in whichsaid check valve includes a closure member and movable valve seatnormally engaging each other, and said check valve opening meansincludes means supporting said first-mentioned seat for movement towardthe valve outlet when said pressure drop occurs, and means connectingsaid supporting means with the check valve seat for moving it away fromsaid closure member.

10. Compressed gas breathing apparatus according to claim 9, in whichsaid supporting means includes an annular disc provided with an axialpassage encircled by said first-mentioned seat, and a diaphragmsupporting said disc and provided with a central opening aligned withsaid passage, the alarm valve also including a spring urging said checkvalve seat toward said closure member. v

1. Compressed gas breathing apparatus comprising a conduit with an inletfor connection to a source of breathing gas under high pressure, anormally closed pneumatically operated control valve with an outlet, anormally closed pneumatically operated alarm valve with an outlet, apressure-reducing demand valve having an inlet connected with said valveoutlets and having an outlet for connection to a facepiece,gas-conducting means connecting the outlet of said conduit with theinlets of said valves, said control valve containing pneumatic pressureactuated means for holding it open as long as said gas pressure remainsabove a predetermined value to thereby connect said conduit with thedemand valve, the alarm valve being formed and constructed to be openedabruptly by the pressure drop across it every time the demand valve isopened while said control valve is close due to reduction in said gaspressure below said pre-determined value, whereby to create a pulse ofgas at the outlet of the demand valve that will signal the user of theapparatus that the control valve has closed.
 2. Compressed gas breathingapparatus according to claim 1, in which said gas-conducting means is apressure reducer.
 3. Compressed gas breathing apparatus according toclaim 2, including a tube connecting said conduit with said pressureactuated means in the control valve for applying said gas pressurethereto to hold the control valve open.
 4. Compressed gas breathingapparatus according to claim 3, in which said control valve includes avalve port encircled by a seat between the inlet and outlet of thatvalve, a closure member, and a spring normally holding said closuremember against said seat, and said pressure actuated means includes apiston operatively connected with said closure member for moving it awayfrom said seat against the resistance of said spring, the control valvehaving a passage connecting said tube with said piston.
 5. Compressedgas breathing apparatus according to claim 4, including means foradjusting the pressure exerted by said spring, whereby to control saidpredetermined value of said gas pressure.
 6. Compressed gas breathingapparatus according to claim 4, including a stem extending through saidvalve port and rigidly connected to said piston and closure member. 7.Compressed gas breathing apparatus according to claim 4, including astem extending through said valve port and rigidly connected to saidpiston and closure member, and a collar threaded on said stem, saidspring being a coil spring encircling said stem and compressed betweensaid collar and valve port.
 8. Compressed gas breathing apparatusaccording to claim 1, in which said alarm valve includes a valve seat, adiaphragm between the seat and the valve outlet, a normaLly closedchamber having said diaphragm as one wall whereby a predetermined gaspressure in the chamber will hold the diaphragm against said seat tomaintain the valve closed, a normally closed check valve for saidchamber, and means actuated by said pressure drop for opening said checkvalve so that the gas pressure at the valve inlet will force thediaphragm away from its seat.
 9. Compressed gas breathing apparatusaccording to claim 8, in which said check valve includes a closuremember and movable valve seat normally engaging each other, and saidcheck valve opening means includes means supporting said first-mentionedseat for movement toward the valve outlet when said pressure dropoccurs, and means connecting said supporting means with the check valveseat for moving it away from said closure member.
 10. Compressed gasbreathing apparatus according to claim 9, in which said supporting meansincludes an annular disc provided with an axial passage encircled bysaid first-mentioned seat, and a diaphragm supporting said disc andprovided with a central opening aligned with said passage, the alarmvalve also including a spring urging said check valve seat toward saidclosure member.